Everything below concerns Sublimation. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-05-23. Numbers and descriptions here follow the published literature rather than marketing material.
Freeze-drying is used for materials whose activity or structure depends on low temperature and low water content. Examples include certain biologics, diagnostic reagents, starter cultures, coffee, and porous inorganic precursors. The dried product forms a cake whose porosity aids rapid wetting and dissolution. Main drawbacks are high energy use, long cycle times, and sensitivity to formulation and equipment variation. Questions remain about how freezing rates and ice morphology affect batch uniformity, especially when moving from laboratory to production scale.
Lyophilization, also called freeze-drying, is a dehydration process in which a solvent, usually water, is frozen and then removed by sublimation under reduced pressure. The method preserves heat-sensitive materials that would degrade in conventional drying. Large-scale use grew during the mid-twentieth century for blood plasma and antibiotics, and it later expanded to vaccines, enzymes, foods, and advanced materials. The process produces a dry, porous solid that usually reconstitutes rapidly. It is distinct from simple evaporation because the solvent bypasses the liquid phase during primary removal.
The process generally proceeds in three stages: freezing, primary drying, and secondary drying. During freezing, controlled cooling converts water into ice and may also crystallize or vitrify solutes. In primary drying, the pressure is lowered below the triple point, and heat is supplied so ice sublimes directly to vapor. Secondary drying removes water that remains bound to the solid matrix, yielding a low final water content. Product temperature must stay below the collapse or glass transition temperature to maintain structure. Cycle design therefore balances shelf temperature, chamber pressure, and time.
The physics of lyophilization couples heat transfer, mass transfer, and phase behavior. Sublimation requires a vapor pressure difference between the ice front and the chamber, and the dried layer adds resistance to vapor flow. Amorphous formulations are characterized by a glass transition temperature of the maximally freeze-concentrated solute, often denoted Tg'. Crystalline bulking agents can provide structure, while amorphous excipients stabilize labile components. Open questions remain about spatial heterogeneity, edge effects, and how laboratory cycles scale to production.
Lyophilization is a drying process in which a solvent, usually water, is removed from a frozen material by sublimation under reduced pressure. The material is first solidified, then placed under vacuum so that ice transitions directly to vapor without a bulk liquid phase. This approach suits heat-sensitive substances that would degrade during conventional evaporation. Primary drying removes unbound ice, while secondary drying reduces water that remains adsorbed to the solid matrix. The result is a porous, lightweight solid that can be reconstituted later.
A typical cycle begins with freezing, sometimes including an annealing step to control ice crystal size. Freezing conditions influence the pore network that later allows vapor escape. During primary drying, shelf temperature and chamber pressure are set so heat enters the product while its temperature stays below the collapse or eutectic point. Secondary drying then raises the shelf temperature to desorb bound water and lower residual moisture. Cycle design depends on formulation, fill volume, container type, and equipment capability.
| Property | Value | Notes |
|---|---|---|
| Common names | Lyophilization; freeze-drying | Terms used interchangeably. |
| Phase change | Sublimation | Ice converts directly to vapor under vacuum. |
| Typical chamber pressure | 0.01–1 mbar | Below the triple point of water. |
| Primary drying product temperature | −40 to −10 °C | Kept below collapse or glass transition temperature. |
| Water content after drying | 0.5–3% w/w | Varies with formulation and cycle. |
A typical cycle begins with freezing, which fixes the material into a solid and determines ice crystal size. Primary drying then raises heat under vacuum so ice sublimes, often near or below the collapse temperature of the formulation. Secondary drying removes bound water that remains after ice is gone, usually by gently warming the product. Each stage balances heat input against pressure to avoid melting or structural damage. Temperature probes and pressure sensors guide the transition between stages.
In practice, lyophilization is slower and more energy intensive than simple drying. Cycle times can range from hours to several days depending on load, container, and formulation. Amorphous materials may require excipients that help preserve structure during freezing and drying. The method is widely used for biological materials, pharmaceuticals, and foods where heat drying would cause unacceptable change. Open questions remain about scaling cycles between laboratory and production equipment, and this gap affects technology transfer.
Lyophilization removes water by freezing a material and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intermediate liquid state. Because the material remains frozen during primary drying, the structure often stays porous. This porous matrix can rehydrate quickly when water is added back. The low pressure also allows vapor to leave the solid matrix without boiling.
The physical chemistry of freezing influences whether a formulation forms an amorphous glass or a crystalline solid. Amorphous systems can collapse if product temperature rises above the glass transition temperature of the freeze concentrate. Crystalline systems may show eutectic melting, where ice and solute melt together at a fixed temperature. Formulators add bulking agents, lyoprotectants, and buffers to preserve structure and biological activity. The optimum cycle keeps product temperature below critical thresholds during primary drying while allowing efficient sublimation.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen so that water becomes ice; then the surrounding pressure is lowered below the vapor pressure of ice. Heat is applied gently so ice changes directly to vapor without passing through a bulk liquid phase. The vapor is collected on a cold condenser, leaving a dry porous matrix. This process differs from simple evaporation because the material remains frozen during the main drying stage.
Secondary drying removes bound water that remains after ice sublimation. Shelf temperature is raised gradually while pressure remains low, reducing water content to a target range. Over-drying can cause brittleness or electrostatic issues, while under-drying affects stability. The endpoint is often judged by pressure rise tests, temperature measurements, or water content analysis. Scale-up depends on matching heat and mass transfer across equipment sizes. Small changes in shelf temperature or pressure can alter cycle length substantially.
Lyophilization, or freeze-drying, removes water from a material by freezing it and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intervening liquid state. It is used for heat-sensitive materials that would degrade in conventional drying. The three stages are freezing, primary drying, and secondary drying, each with distinct temperature and pressure requirements. In practice, cycle design balances these variables.
Freeze-drying is distinct from simple evaporation and from spray drying. Evaporation removes water at temperatures above freezing, while spray drying rapidly dries droplets in a heated gas stream. Lyophilization avoids high temperatures, which can be useful for heat-sensitive materials such as proteins, vaccines, and some foods. The porous cake produced by sublimation dissolves or rehydrates more quickly than a dense dried mass. Not all materials tolerate freezing or the pH shifts that can occur as solutes concentrate during ice formation.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and fixes the structure of the sample. After freezing, primary drying lowers pressure so ice changes directly to vapor without passing through a liquid phase. Secondary drying then removes bound water that remains after ice sublimation. The result is a dry, porous solid that often retains its original shape.
The low pressure used during drying allows water vapor to move from the ice surface to a cold condenser. Energy supplied as heat drives sublimation but must stay below the collapse temperature of the frozen matrix. If the product becomes too warm, the frozen structure may soften or melt, reducing pore formation and slowing drying. Formulations often include bulking agents, stabilizers, or buffers to support a rigid cake. The final moisture content depends on formulation, freezing rate, and the length of secondary drying.
252Cf(12C,αxn)260−xNo (x=3?) This reaction was studied at the LBNL in 1961 as part of their search for element 104. They detected 8.2 MeV alpha particles with a half-life of 15 s. This activity was assigned to a Z=102 isotope. Later work suggests an assignment to 257No, resulting most likely from the α3n channel with the 252Cf component of the californium target.
== Hybridization == Many species that share the same genus have been known to interbreed and create hybrids. Many species of crotalid rattlesnakes have been documented hybridizing in their natural habitats and in captivity. In southwestern New Mexico the Mojave rattlesnake is known to hybridize with the Prairie rattlesnake. These hybrids have been shown to have an overall lower body condition than either parent species. Experiments with hybrids between C. viridis and C. scutulatus have shown no advantage when it comes to hunting and the metrics are about the same across all species. The hybridization of rattlesnake species can also lead to a change in the overall venom toxicity and composition. This change can lead to a difficulty in treating bites. Rattlesnakes offer the best example for venom differences across the genus with many different species possessing different venom types. It is believed that hybridization is one of the leading causes for this variation in venom types and envenoming strategies.
== Nutrition == A study by the National University of Singapore showed that Chinese dark soy sauce contains 10 times the antioxidants of red wine. Unpasteurized soy sauce is rich in lactic acid bacteria and of excellent anti-allergic potential. Soy sauce does not contain the level of isoflavones associated with other soy products, such as tofu or edamame. It can also be very salty, having a salt content between 14 and 18%. Low-sodium soy sauces are made, but it is difficult to make soy sauce without using some quantity of salt as an antimicrobial agent. A serving of 100 millilitres (3.5 imp fl oz; 3.4 US fl oz) of soy sauce contains, according to the USDA:
=== Concept === Many airports had terminals too small for "aerobuses". In the West, the solution to this involved constructing greater airport capacity. By contrast, Soviet aviation research institutes addressed ways of increasing passenger throughput without the need for additional airport capacity. Many Soviet airports also had surfaces too weak for "aerobuses". The Soviet solution again favoured adapting aircraft to existing conditions, rather than reconstructing airports. The aerobus thus had to match the ground loadings of existing airliners. This called for complex multi-wheel landing gear. The Soviet solution to the airport capacity issue involved passengers loading and unloading their own luggage into and from the aircraft. This was eventually called "the luggage at hand system" (Russian: "система «багаж с собой»"; transliterated: "sistyema bagazh s soboy"). Soviet aviation journalist Kim Bakshmi described it (at its ultimate) thus: "One arrives five minutes prior to departure, buys oneself a ticket on board the aircraft, hangs one's coat next to the seat and places one's bag or suitcase nearby." Taking suitcases into the cabin, as in trains, was studied, but necessitated a 3 m fuselage extension with a 350-seat capacity. To avoid this, passengers were to deposit their luggage in underfloor compartments as they entered the airliner. Ideas similar to the "luggage at hand system" were briefly addressed in the West. Airbus studied such an arrangement in the mid-1970s.
== Biological roles == Human uses of AGPs include the use of gum arabic in the food and pharmaceutical industries because of natural properties in thickening and emulsification. AGPs in cereal grains have potential applications in biofortification, as sources of dietary fibre to support gut bacteria and protective agents against ethanol toxicity. AGPs are found in a wide range of plant tissues, in secretions of cell culture medium of root, leaf, endosperm and embryo tissues, and some exudate producing cell types such as stylar canal cells. AGPs have been shown to regulate many aspects of plant growth and development including male-female recognition in reproduction organs, cell division and differentiation in embryo and post-embryo development, seed mucilage cell wall development, root salt tolerance and root-microbe interactions. These studies suggest that they are multifunctional, similar to what is found in mammalian proteoglycans/glycoproteins. Conventional methods to study functions of AGPs include the use of β-glycosyl (usually glucosyl) Yariv reagents and monoclonal antibodies (mAbs). β-Glycosyl Yariv reagents are synthetic phenylazo glycoside probes that specifically, but not covalently, bind to AGPs and can be used to precipitate AGPs from solution. They are also used commonly as histochemical stains to probe the locations and distribution of AGPs. A number of studies have shown that addition of β-Yariv reagents to plant growth medium can inhibit seedling growth, cell elongation, block somatic embryogenesis and fresh cell wall mass accumulation.
Sources: en.wikipedia.org
While many other authors had published works of fantasy before Tolkien, the great success of The Hobbit and The Lord of the Rings led directly to a popular resurgence and the shaping of the modern fantasy genre. This has caused Tolkien to be popularly identified as the "father" of modern fantasy literature—or, more precisely, of high fantasy, as in the work of authors such as Ursula Le Guin and her Earthsea series. In 2008 The Times ranked him sixth on a list of "The 50 greatest British writers since 1945", and in 2024, Forbes ranked him #60 on a list of 101 greatest authors of all time. His influence has extended to music, including the Danish group the Tolkien Ensemble's setting of all the poetry in The Lord of the Rings to their vocal music; and to a broad range of games set in Middle-earth. Among literary allusions to Tolkien, he appears as the elderly "Professor J. B. Timbermill" in all five novels in J. I. M. Stewart's series A Staircase in Surrey. The scholar Tom Shippey describes Tolkien as the "author of the [20th] century", and states that "I do not think any modern writer of epic fantasy has managed to escape the mark of Tolkien, no matter how hard many of them have tried". John Clute, writing in The Encyclopedia of Fantasy, similarly credits Tolkien with being "the twentieth-century's single most important author of fantasy". His work has had a massive impact on Western pop culture, and remains extremely influential.
== Prevention == There are no methods for preventing the manifestation of the pathology of MSUD in infants with two defective copies of the BCKD gene. However, genetic counselors may consult with couples to screen for the disease via DNA testing. DNA testing is also available to identify the disease in an unborn child in the womb.
=== Semen displacement === The shape of the human penis is thought to have evolved as a result of sperm competition. Semen displacement is an adaptation of the shape of the penis to draw foreign semen away from the cervix. This means that a male can displace a rival male's sperm from the female reproductive tract before replacing it with his own. Semen displacement has two main benefits for a male. Firstly, by displacing a rival male's sperm, the risk of the rival sperm fertilising the egg is reduced. Secondly, the male replaces the rival's sperm with his own, thereby increasing the probability of his fertilising the egg and successfully reproducing with the female. However, males have to ensure they do not displace their own sperm. It is thought that the relatively quick loss of erection after ejaculation, penile hypersensitivity following ejaculation, and the shallower, slower thrusting of the male after ejaculation prevent this from occurring. The coronal ridge is the part of the human penis thought to have evolved to allow for semen displacement. Research has studied how much semen is displaced by differently shaped artificial genitals. This research showed that, when combined with thrusting, the coronal ridge of the penis is able to remove the seminal fluid of a rival male from within the female reproductive tract. It does this by forcing the semen under the frenulum of the coronal ridge, causing it to collect behind the coronal ridge shaft.
==== Corneal Allogenic Intrastromal Ring Segments (CAIRS) ==== Corneal Allogenic Intrastromal Ring Segment Keratoplasty (CAIRS Keratoplasty) is a modern surgical technique used in the treatment of keratoconus. It involves implanting finely shaped pieces of donor corneal tissue into the corneal stroma to reinforce and reshape the weakened, ectatic cornea, thereby improving both corneal structure and visual clarity. Because CAIRS uses biological graft material and has demonstrated strong outcomes with a favourable safety profile, it is formally recognised as a corneal transplantation procedure by health funding authorities in Australia, the United Kingdom, Japan, Germany, Brazil, the Netherlands, and a number of other countries. In contrast to traditional synthetic intrastromal corneal ring segments (ICRS) made from materials such as PMMA, CAIRS keratoplasty uses preserved allogeneic corneal tissue. This biological compatibility reduces the likelihood of complications sometimes seen with non-organic implants, including extrusion, infection, or chronic foreign body reaction. The CAIRS technique was pioneered by Dr Soosan Jacob, who first introduced it in 2018 through a large case series published in the Journal of Refractive Surgery. One of its key strengths is its suitability for corneas with irregular or decentered cones. The donor segments can be individually designed to achieve targeted corneal flattening and astigmatism improvement.
Sources: en.wikipedia.org
Phenelzine, also known as 2-phenylethylhydrazine or phenylethylamine hydrazide, is a phenethylamine and hydrazine derivative. It is the hydrazide of β-phenethylamine and can also be referred to as N-aminophenethylamine.
=== Batch === In a batch process, all the ingredients are combined and the reactions proceed without any further input. Batch fermentation has been used for millennia to make bread and alcoholic beverages, and it is still a common method, especially when the process is not well understood. However, it can be expensive because the fermentor must be sterilized using high pressure steam between batches. Strictly speaking, there is often addition of small quantities of chemicals to control the pH or suppress foaming. Batch fermentation goes through a series of phases. There is a lag phase in which cells adjust to their environment; then a phase in which exponential growth occurs. Once many of the nutrients have been consumed, the growth slows and becomes non-exponential, but production of secondary metabolites (including commercially important antibiotics and enzymes) accelerates. This continues through a stationary phase after most of the nutrients have been consumed, and then the cells die.
A steady state, on the other hand, is not necessarily an equilibrium state in the chemical sense. For example, in a radioactive decay chain the concentrations of intermediate isotopes are constant because the rate of production is equal to the rate of decay. It is not a chemical equilibrium because the decay process occurs in one direction only. Thermodynamic equilibrium is characterized by the free energy for the whole (closed) system being a minimum. For systems at constant volume the Helmholtz free energy is minimum and for systems at constant pressure the Gibbs free energy is minimum. Thus a metastable state is one for which the free energy change between reactants and products is not minimal even though the composition does not change in time. The existence of this minimum is due to the free energy of mixing of reactants and products being always negative. For ideal solutions the enthalpy of mixing is zero, so the minimum exists because the entropy of mixing is always positive. The slope of the reaction free energy, δGr with respect to the reaction coordinate, ξ, is zero when the free energy is at its minimum value.
Deaths from snakebites are uncommon in many parts of the world, but are still counted in tens of thousands per year in India. Snakebite can be treated with antivenom made from the venom of the snake. To produce antivenom, a mixture of the venoms of different species of snake is injected into the body of a horse in ever-increasing dosages until the horse is immunized. Blood is then extracted; the serum is separated, purified and freeze-dried. The cytotoxic effect of snake venom is being researched as a potential treatment for cancers. Gila monsters produce compounds that reduce plasma glucose; one of these substances is now used in the anti-diabetes drug exenatide (Byetta), a glucagon-like peptide-1 (GLP-1) receptor agonist like semiglutide (Ozempic). Another toxin from Gila monster saliva has been studied for use as an anti-Alzheimer's drug. Geckos have also been used as folk medicine, especially in China, without any evidence that they have any active compounds. Turtles have been used in Chinese traditional medicine for thousands of years, with every part of the turtle believed to have medical benefits (again, without scientific evidence). Growing demand for turtle meat has placed pressure on vulnerable wild populations of turtles.
=== Pharmacokinetics === While apomorphine has lower bioavailability when taken orally, due to not being absorbed well in the GI tract and undergoing heavy first-pass metabolism, it has a bioavailability of 100% when given subcutaneously. It reaches peak plasma concentration in 10–60 minutes. Ten to twenty minutes after that, it reaches its peak concentration in the cerebrospinal fluid. Its lipophilic structure allows it to cross the blood–brain barrier. Apomorphine has a high clearance rate (3–5 L/kg/hr) and is mainly metabolized and excreted by the liver. It is likely that while the cytochrome P450 system plays a minor role, most of apomorphine's metabolism happens via auto-oxidation, O-glucuronidation, O-methylation, N-demethylation, and sulfation. Only 3–4% of the apomorphine is excreted unchanged and into the urine. The half-life is 30–60 minutes, and the effects of the injection last for up to 90 minutes.
Sources: en.wikipedia.org
Yes. Lyophilization and freeze-drying are synonyms for the same vacuum-assisted sublimation process. The term lyophilization is more common in pharmaceutical and laboratory settings, while freeze-drying is widely used in food and general contexts.
Reduced pressure lowers the boiling point of water and allows ice to sublime below its triple point. Without sufficient vacuum, melting or boiling may occur instead of sublimation, which can damage the product structure.
Heat and mass transfer limit drying once the ice front recedes. The dried layer insulates the frozen core and resists vapor flow, so increasing shelf temperature too quickly can cause collapse or meltback.
Freezing only converts liquid to solid. Lyophilization adds vacuum and controlled warming so frozen solvent sublimes, leaving a dry porous solid. The two steps are related but not interchangeable.